Abstract. In this paper, core-shell TiO2/polystyrene (TiO2/PS) microspheres with superhydrophobic properties were prepared via a facile method. Our method needs neither special apparatus nor complicated chemical treatment. The whole process includes two steps: firstly, coupling agent was used to modify TiO2 by sol-gel method; secondly, fabrication of TiO2/PS dispersions was carried out via in-situ free-radical polymerization strategy. The component and structure of the TiO2/PS particles were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The TiO2 gel particles with average diameter of 1 µm exhibited irregular spherical shape and obvious aggregation. Compared with the TiO2 particles, the resulting TiO2/PS particulates showed regular spherical shape, better dispersion and bigger size. By directly depositing the resulted TiO2/PS dispersion on a Cu foil, the coating showed superhydrophobic property which was reflected by the contact angle (CA) of water on the surface with high water adhesion. The apparent CA of water is 153.5±1.5°, suggesting that this composite possesses well superhydrophobicity.
4-aminopyridine (4AP) is a potassium (K+) channel blocker used clinically to improve walking in people with multiple sclerosis (MS). Multiple derivatives of 4AP capable of blocking K+ channels have been reported including three radiolabeled with positron emitting isotopes for imaging demyelinated lesions using PET. Here, we describe 3-fluoro-5-methylpyridin-4-amine (5Me3F4AP), a novel K+ channel blocker with potential application in PET. 5Me3F4AP has comparable potency to 4AP and 3-fluoro-4-aminopyridine (3F4AP). Compared to 3F4AP, 5Me3F4AP is more lipophilic (logD = 0.664 ± 0.005 vs. 0.414 ± 0.002) and slightly more basic (pKa = 7.46 ± 0.01 vs. 7.37 ± 0.07). In addition, 5Me3F4AP appears to be more permeable to an artificial brain membrane and stable towards oxidation by the cytochrome P450 enzyme family 2 subfamily E member 1 (CYP2E1), responsible for the metabolism of 4AP and 3F4AP. Taken together, 5Me3F4AP has promising properties for PET imaging warranting additional investigation.
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